Acyclic carboxamides having a physiological cooling effect

ABSTRACT

Compositions are disclosed having a physiological cooling action on the skin. The compositions contain, as the active ingredient, certain acyclic tertiary and secondary carboxamides.

This is a division of application Ser. No. 036,662, filed May 7, 1979, now U.S. Pat. No. 4,230,688, as a continuation of Ser. No. 768,219, filed Feb. 14, 1977, now U.S. Pat. No. 4,153,679, as a divisional application of Ser. No. 351,357, filed Apr. 16, 1973, now abandoned.

This invention relates to ingestible, topical and other compositions having a physiological cooling effect on the skin and on the mucous membranes of the body, particularly the mucous membranes of the nose and bronchial tract.

Menthol is well known for its physiological cooling effect on the skin and mucous membranes of the mouth and has been extensively used as a flavouring agent (menthol being a major constituent of oil of peppermint) in foodstuffs, beverages, dentifrices, mouthwashes, etc. and as a component in a wide range of toiletries, liniments and lotions for topical application. Menthol is also a well known tobacco additive for producing a "cool" sensation in the mouth when smoking. Carvomenthol has also been reported as having a physiological cooling effect and so also have N,N-dimethyl-2-ethyl butanamide and N,N-diethyl-2-ethyl butanamide, see French Pat. No. 1,572,332.

It is well established that the "cooling" effect of menthol is a physiological effect due to the direct action of menthol on the nerve endings of the human body responsible for the detection of hot or cold and is not due to latent heat of evaporation. It is believed that the menthol acts as a direct stimulus on the cold receptors at the nerve endings which in turn stimulate the central nervous system.

Although menthol is well established as a physiological coolant its use, in some compositions, is circumscribed by its strong minty odour.

The present invention is based on the discovery that certain other organic compounds, which can be readily synthesised, have a physiological cooling effect similar to that obtained with menthol, but do not have the strong minty odour. In many cases the compounds have little or no odour at all. Such compounds therefore find utility as additives in a wide range of ingestible and topical compositions. More particularly they find utility as components in compositions for nasal application and in vapour rubs and liniments.

The compounds having a physiological cooling effect and utilisable in accordance with the present invention are amides of the formula: ##STR1## where R' and R", when taken separately, are each hydrogen, C₁ -C₅ alkyl or C₁ -C₈ hydroxyalkyl and provide a total of no more than 8 carbon atoms, with the proviso that when R' is hydrogen R" may also be alkylcarboxyalkyl of up to 6 carbon atoms;

R' and R", when taken together, represent an alkylene group of up to 6 carbon atoms, the opposite ends of which group are attached to the amide nitrogen atom thereby to form a nitrogen heterocycle, the carbon atom chain of which may optionally be interrupted by oxygen;

R₁ is hydrogen or C₁ -C₅ alkyl; and

R₂ and R₃ are each C₁ -C₅ alkyl;

with the provisos that

(i) R₁, R₂ and R₃ together provide a total of at least 5 carbon atoms, preferably from 5-10 carbon atoms; and

(ii) when R₁ is hydrogen, R₂ is C₂ -C₅ alkyl and R₃ is C₃ -C₅ alkyl and at least one of R₂ and R₃ is branched, preferably in an alpha or beta position relative to the carbon atom marked (*) in the formula.

Where the compounds used in this invention have an asymmetric carbon atom either optical isomer may be used in pure form but generally a mixture of optical isomers will be used. In some cases the degree of cooling produced by the compounds on the skin will differ as between optical isomer, in which case one or other isomer may be preferred.

The preferred amides used in this invention are the tertiary compounds, i.e. those where each of R₁, R₂ and R₃ is C₁ -C₅ alkyl, especially those where R₁ is methyl, ethyl or n-propyl and at least one of R₂ and R₃ is a branched chain group having branching in an alpha or beta position relative to the C atom marked (*) in the formula. Also preferred are non-substituted amides, i.e. where R' is H, and disubstituted amides where R' and R" are methyl or ethyl. A further preferred group consists of amides of the formula given where R₁ is hydrogen and at least one of R₂ and R₃ is branched in an alpha position relative to the carbon atom marked * in the formula.

The amides may readily be prepared by conventional techniques, for example, by reaction of an acid chloride of the formula R₁ R₂ R₃ COCl with an amine of the formula HNR'R" in the presence of a hydrogen chloride acceptor. Such reactions are entirely conventional and the procedures involved will readily be understood by persons skilled in the art.

Typical amides usable in the compositions of this invention are listed below in the Table together with an indication of their cooling activity; the more stars the greater the activity, i.e. the greater the degree of cooling produced by a given quantity of the compound.

    __________________________________________________________________________     R.sub.1                                                                             R.sub.2                                                                              R.sub.3                                                                               R'   R"        Activity                                      __________________________________________________________________________     CH.sub.3                                                                            iso-C.sub.3 H.sub.7                                                                  iso-C.sub.3 H.sub.7                                                                   H    C.sub.2 H.sub.5                                                                          * * * * *                                     CH.sub.3                                                                            iso-C.sub.3 H.sub.7                                                                  iso-C.sub.3 H.sub.7                                                                   H    iso-C.sub.3 H.sub.7                                                                      * * * * *                                     CH.sub.3                                                                            iso-C.sub.3 H.sub.7                                                                  iso-C.sub.3 H.sub.7                                                                   H    CH.sub.3  * * * * *                                     CH.sub.3                                                                            iso-C.sub.3 H.sub.7                                                                  iso-C.sub.3 H.sub.7                                                                   H    HOCH.sub.2 C(CH.sub.3).sub.2                                                             * * * * *                                     CH.sub.3                                                                            iso-C.sub.3 H.sub.7                                                                  iso-C.sub.3 H.sub.7                                                                   CH.sub.3                                                                            CH.sub.3  * * * * *                                     CH.sub.3                                                                            iso-C.sub.3 H.sub.7                                                                  iso-C.sub.3 H.sub.7                                                                   H    tert-C.sub.4 H.sub.9                                                                     * * * * *                                     C.sub.2 H.sub.5                                                                     C.sub.2 H.sub.5                                                                      iso-C.sub.3 H.sub.7                                                                   H    C.sub.2 H.sub.5                                                                          * * * * *                                     C.sub.2 H.sub.5                                                                     C.sub. 2 H.sub.5                                                                     iso-C.sub.3 H.sub.7                                                                   C.sub.2 H.sub.5                                                                     C.sub.2 H.sub.5                                                                          * * * * *                                     CH.sub.3                                                                            iso-C.sub.3 H.sub.7                                                                  iso-C.sub.4 H.sub.9                                                                   H    C.sub.2 H.sub.5                                                                          * * * * *                                     C.sub.2 H.sub.5                                                                     iso-C.sub.3 H.sub.7                                                                  iso-C.sub.3 H.sub.7                                                                   H    C.sub.2 H.sub.5                                                                          * * * * *                                     H    sec-C.sub.4 H.sub.9                                                                  sec-C.sub.4 H.sub.9                                                                   H    sec-C.sub.4 H.sub.9                                                                      * * * * *                                     CH.sub.3                                                                            iso-C.sub.3 H.sub.7                                                                  n-C.sub.4 H.sub.9                                                                     CH.sub.3                                                                            CH.sub.3  * * * * *                                     H    iso-C.sub.4 H.sub.9                                                                  sec-C.sub.4 H.sub.9                                                                   H    C.sub.2 H.sub.5                                                                          * * * * *                                     CH.sub.3                                                                            sec-C.sub.4 H.sub.9                                                                  sec-C.sub.4 H.sub.9                                                                   H    C.sub.2 H.sub.5                                                                          * * * * *                                     CH.sub.3                                                                            iso-C.sub.3 H.sub.7                                                                  iso-C.sub.3 H.sub.7                                                                   H    C.sub.2 H.sub.5 OOCCH.sub.2                                                              * * * *                                       C.sub.2 H.sub.5                                                                     C.sub. 2 H.sub.5                                                                     C.sub.2 H.sub.5                                                                       H    C.sub.2 H.sub.5                                                                          * * * *                                       CH.sub.3                                                                            sec-C.sub.4 H.sub.9                                                                  sec-C.sub.4 H.sub.9                                                                   H    iso-C.sub.3 H.sub.7                                                                      * * * *                                       CH.sub.3                                                                            iso-C.sub.3 H.sub.7                                                                  n-C.sub.4 H.sub.9                                                                     H    C.sub.2 H.sub.5                                                                          * * * *                                       CH.sub.3                                                                            iso-C.sub.4 H.sub.9                                                                  iso-C.sub.4 H.sub.9                                                                   H    C.sub.2 H.sub.5                                                                          * * * *                                       CH.sub.3                                                                            CH.sub.3                                                                             iso-C.sub.4 H.sub.9                                                                   H    C.sub.2 H.sub.5                                                                          * * * *                                       CH.sub.3                                                                            CH.sub.3                                                                             iso-C.sub.4 H.sub.9                                                                   CH.sub.3                                                                            CH.sub.3  * * * *                                       H    iso-C.sub.4 H.sub.9                                                                  iso-C.sub.4 H.sub.9                                                                   H    C.sub.2 H.sub.5 OOCCH.sub.2                                                              * * * *                                       H    C.sub.2 H.sub.5                                                                      sec-C.sub.4 H.sub.9                                                                   CH.sub.3                                                                            CH.sub.3  * * * *                                       H    C.sub.2 H.sub.5                                                                      sec-C.sub.4 H.sub.9                                                                   H    C.sub.2 H.sub.5                                                                          * * * *                                       H    iso-C.sub.4 H.sub.9                                                                  sec-C.sub.4 H.sub.9                                                                   H    C.sub.2 H.sub.5 OOCCH.sub.2                                                              * * * *                                       H    iso-C.sub.4 H.sub.9                                                                  sec-C.sub.4 H.sub.9                                                                   H    HOCH.sub.2 C(CH.sub.3).sub.2                                                             * * * *                                       CH.sub.3                                                                            iso-C.sub.4 H.sub.9                                                                  iso-C.sub.4 H.sub.9                                                                    ##STR2##      * * * *                                       CH.sub.3                                                                            iso-C.sub.3 H.sub.7                                                                  iso-C.sub.3 H.sub.7                                                                   H    C.sub.2 H.sub.5 OOCCH.sub.2                                                              * * *                                         C.sub.2 H.sub.5                                                                     C.sub.2 H.sub.5                                                                      C.sub.2 H.sub.5                                                                       H    HOCH.sub.2 C(CH.sub.3).sub.2                                                             * * *                                         CH.sub.3                                                                            sec-C.sub.4 H.sub.9                                                                  sec-C.sub.4 H.sub.9                                                                   H    HOCH.sub.2 CH.sub.2                                                                      * * *                                         CH.sub.3                                                                            sec-C.sub.4 H.sub.9                                                                  sec-C.sub.4 H.sub.9                                                                   H    H         * * *                                         CH.sub.3                                                                            iso-C.sub.4 H.sub.9                                                                  iso-C.sub.4 H.sub.9                                                                   H    C.sub.2 H.sub.5                                                                          * * *                                         H    iso-C.sub.3 H.sub.7                                                                  iso-C.sub.4 H.sub.9                                                                   H    C.sub.2 H.sub.5                                                                          * * *                                         H    iso-C.sub.4 H.sub.9                                                                  iso-C.sub.4 H.sub.9                                                                   H    C.sub.2 H.sub.5 OOCCH.sub.2                                                              * * *                                         H    iso-C.sub.3 H.sub.7                                                                  iso-C.sub.4 H.sub.9                                                                   H    C.sub.2 H.sub.5 OOCCH.sub.2                                                              * *                                           H    C.sub.2 H.sub.5                                                                      iso-C.sub.3 H.sub.7                                                                   CH.sub.3                                                                            CH.sub.3  * *                                           H    iso-C.sub.4 H.sub.9                                                                  iso-C.sub.4 H.sub.9                                                                   H    HOCH.sub.2 C(CH.sub.3).sub.2                                                             * *                                           H    C.sub.2 H.sub.5                                                                      iso-C.sub.5 H.sub.11                                                                  H    C.sub.2 H.sub.5                                                                          * *                                           CH.sub.3                                                                            iso-C.sub.3 H.sub.7                                                                  ios-C.sub.4 H.sub.9                                                                    ##STR3##      * *                                           H    iso-C.sub.3 H.sub.7                                                                   iso-C.sub.3 H.sub.7                                                                  H    iso-C.sub.3 H.sub.7                                                                      * *                                           C.sub.2 H.sub.5                                                                     C.sub.2 H.sub.5                                                                      C.sub.2 H.sub.5                                                                       CH.sub.3                                                                            CH.sub.3  *                                             CH.sub.3                                                                            C.sub.2 H.sub.5                                                                      C.sub.2 H.sub.5                                                                       CH.sub.3                                                                            CH.sub.3  *                                             CH.sub.3                                                                            C.sub.2 H.sub.5                                                                      C.sub.2 H.sub.5                                                                       H    C.sub.2 H.sub.5 OOCCH.sub.2                                                              *                                             CH.sub.3                                                                            CH.sub.3                                                                             ios-C.sub.4 H.sub.9                                                                   H    C.sub.2 H.sub.5 OOCCH.sub.2                                                              *                                             H    CH.sub.3                                                                             iso-C.sub.4 H.sub.9                                                                   H    HOCH.sub.2 C(CH.sub.3).sub.2                                                             *                                             H    C.sub.2 H.sub.5                                                                      sec-C.sub.4 H.sub.9                                                                   H    HOCH.sub.2 C(CH.sub.3).sub.2                                                             *                                             CH.sub.3                                                                            iso-C.sub.3 H.sub.7                                                                  iso-C.sub.3 H.sub.7                                                                   H    H         *                                             C.sub.2 H.sub.5                                                                     C.sub.2 H.sub.5                                                                      iso-C.sub.3 H.sub.7                                                                   H    H         *                                             __________________________________________________________________________

Certain amides used in the present invention and preparable by the above described method are novel compounds and as such represent a further aspect of the present invention. The novel compounds are mono-substituted tertiary amides of the formula: ##STR4## where R₁, R₂ and R₃ are each C₁ -C₅ alkyl and together provide a total of at least 5, preferably 5-10 carbon atoms; and R' is C₁ -C₅ alkyl, C₁ -C₈ hydroxyalkyl or alkylcarboxyalkyl of up to 8 carbon atoms. In this group R₁ is preferably methyl, ethyl or n-propyl and one or both of R₂ and R₃ is branched in an alpha or beta position relative to the carbon atom marked (*).

The compounds of the above formulae find utility in a wide variety of compositions for consumption by or application to the human body. Broadly speaking, these compositions can be divided into comestible and topical compositions, both terms being taken in their broadest possible sense. Thus comestible is to be taken as including not only foodstuffs and beverages taken into the mouth and swallowed, but also other orally ingested compositions taken for reasons other than their nutritional value, e.g. indigestion tablets, antacid preparations, laxatives etc. Comestible compositions are also to be taken to include edible compositions taken by mouth, but not necessarily swallowed, e.g. chewing gum. Topical compositions are to be taken as including not only compositions such as perfumes, powders and other toiletries, lotions, liniments, oils and ointments applied to the external surfaces of the human body, whether for medical or other reasons, but also compositions applied to, or which, in normal usage, come in contact with, internal mucous membranes of the body, such as those of the nose, mouth, or throat, whether by direct or indirect application or inhalation, and thus include nasal and throat sprays, dentifrice, mouthwash and gargle compositions. Also included within the present invention are toilet articles such as cleansing tissues and toothpicks impregnated or coated with the active cooling compound.

A further class of compositions included within the scope of this invention are tobacco and associated articles e.g. pipe and cigarette filters, especially filter tips for cigarettes.

The compositions of this invention will contain an amount of the active cooling compound sufficient to stimulate the cold receptors in the areas of the skin or mucous membrane with which the compositions come into contact and thereby promote the desired cold sensation. As the degree and longevity of cooling sensation varies from compound to compound the quantity of stimulant used in each composition will vary widely. As a guide, it may be said that, with the more active compounds, a significant cooling sensation, which, in some cases, may persist for several hours, is achieved upon application to the skin of as little as 0.05 ml. of a 1.0% weight percent solution of the active ingredient in ethanol. For the less active compounds a significant cooling effect is achieved only with more concentrated solutions, e.g. 5.0% by weight or more of the active ingredient. It must also be admitted that such skin tests are somewhat subjective, some individuals experiencing a greater or lesser cooling sensation than others when subjected to the same test.

In formulating the compositions of this invention the active cooling compound will usually be incorporated into a carrier which may be completely inert or which may be or contain other active ingredients. A wide variety of carriers will be suitable, depending upon the end use of the composition, such carriers including solids, liquids, emulsions, foams and gels. Typical carriers for the active cooling compound include aqueous or alcoholic solutions; oils and fats such as hydrocarbon oils, fatty acid esters, long chain alcohols and silicone oils; finely divided solids such as starch or talc; cellulosic materials such as paper tissue; tobacco; low-boiling hydrocarbons and halohydrocarbons used as aerosol propellants; gums and natural or synthetic resins.

In most compositions according to the invention the carrier will be or contain as an adjuvant one or more of the following: an antacid, antiseptic or analgesic, a flavourant, colourant, or odourant, or a surfactant.

The following illustrate the range of compositions into which the active cooling compounds can be incorporated:

1. Edible or potable compositions including alcoholic and non-alcoholic beverages, confectionery, chewing gum; cachous; ice cream; jellies;

2. Toiletries including after shave lotions, shaving soaps, creams and foams, toilet water, deodorants and antiperspirants, "solid colognes", toilet soaps, bath oils and salts, shampoos, hair oils, talcum powders, face creams, hand creams, sunburn lotions, cleansing tissues, dentifrices, toothpicks, mouthwashes, hair tonics, eyedrops.

3. Medicaments including antiseptic ointments, pile ointments, liniments, lotions, decongestants, counter-irritants, cough mixtures, throat lozenges, antacid and indigestion preparations, oral analgesics;

4. Tobacco preparations including cigars, cigarettes, pipe tobacco, chewing tobacco and snuff; tobacco filters, especially filter tips for cigarettes.

5. Miscellaneous compositions such as water soluble adhesive compositions for envelopes, postage stamps, adhesive labels etc.

Particular preparations according to the invention are discussed in more detail below.

Edible and Potable Compositions

The edible and potable compositions of this invention will contain the active cooling compound in combination with an edible carrier and usually a flavouring or colouring agent. The particular effect of the cooling compounds is to create a cool or fresh sensation in the mouth, and in some cases, even in the stomach, and therefore the compounds find particular utility in sugar-based confectionery such as chocolate, boiled sweets and candy, in ice cream and jellies and in chewing gum. The formulation of such confections will be by ordinary techniques and according to conventional recipes and as such forms no part of this invention. The active compound will be added to the recipe at a convenient point and in amount sufficient to produce the desired cooling effect in the final product. As already indicated, the amount will vary depending upon the particular compound, the degree of cooling effect desired and the strength of other flavourants in the recipe. For general guidance, however, amounts in the range 0.1 to 5% by weight based on the total composition will be found suitable.

Similar considerations apply to the formulation of beverages. Generally speaking the compounds will find most utility in soft drinks e.g. fruit squashes, lemonade, cola etc., but may also be used in alcoholic beverages. The amount of compound used will generally be in the range 0.1 to 2.5% by weight based on the total composition.

Toiletries

Because of the cooling sensation imparted to the skin, a major utility of the cooling compounds will be in a wide range of toilet preparations and toilet articles. The particular preparations discussed below are to be taken as exemplary.

A major utility will be in after shave lotions, toilet water etc., where the compound will be used in alcoholic or aqueous alcoholic solution, such solutions usually also containing a perfume or mild antiseptic or both. The amount of compound added to the formulation will usually be in the range 0.1 to 10% by weight based on the total composition.

Another field of utility will be in soaps, shampoos, bath oils etc. where the compound will be used in combination with an oil or fat or a natural or synthetic surfactant e.g. a fatty acid salt or a lauroylsulphate salt, the composition usually also containing an essential oil or perfume. The range of soap compositions will include soaps of all kinds e.g. toilet soaps, shaving soaps, shaving foams etc. Usually the compound will be added to the formulation in amount of from 0.1 to 10% by weight.

A further class of toilet compositions into which the compounds may be incorporated includes cosmetic creams and emollients, such creams and emollients usually comprising a base emulsion and optionally a range of ingredients such as wax, preservative, perfume, antiseptics, astringents, pigments etc. Also included within this class are lipstick compositions such compositions usually comprising an oil and wax base into which the compound can be incorporated along with the conventional ingredients, i.e. pigments, perfumes etc. Once again the formulation of such compositions, apart from the incorporation of the cooling compound, usually in an amount of from 0.05 to 10% by weight, is conventional.

Compositions for oral hygiene containing the cooling compounds include mouthwash, gargle and dentifrice compositions. The first two may be considered together and will usually comprise an aqueous, alcoholic, or aqueous-alcoholic solution of an antiseptic often coloured or flavoured for palatability, to which the coolant is added in an amount of from 0.1 to 1.0% by weight.

Dentifrice compositions may be of the solid block, powder, paste or liquid type and will usually comprise a finely divided abrasive or polishing material, e.g. precipitated chalk, silica, magnesium silicate, aluminum hydroxide or other similar materials well known in the art, and a detergent or foaming agent. Optional ingredients which may also be included are flavouring agents and colourants, antiseptics, lubricants, thickeners, emulsifiers or plasticizers. The amount of coolant added in such compositions will generally be from 0.1 to 5.0% by weight based on the total composition.

Medicaments

Because of their cooling effect on the skin and on the mucous membranes of the mouth, throat and nose and of the gastrointestinal tract the cooling compounds may be used in a variety of oral medicines, nasal and throat sprays, and topical compositions, particularly where a counter-irritant is required. In particular the coolants may be formulated into antacid and indigestion remedics, in particular those based on sodium bicarbonate, magnesium oxide, calcium or magnesium carbonate, aluminum or magnesium hydroxide or magnesium trisilicate. In such compositions the coolant will usually be added in an amount of from 0.01 to 2.0% by weight.

The coolants may also be included in oral analgesic compositions e.g. with acetylsalicyclic acid or its salts, and in nasal decongestants e.g. those containing ephedrine.

Tobacco Preparations

The coolants of this invention may be incorporated directly into tobacco to give a cool effect when smoking but without the attendant strong and characteristic odour which is associated with mentholated tobacco and cigarettes. However, a more advantageous utilisation of the coolants of this invention is in pipe or cigarette filters, in particular, filter tipped cigarettes. The pad of filter material, which may be of any of the well known types, e.g. cellulose acetate, paper, cotton α-cellulose or asbestos fiber, is simply impregnated with an alcoholic solution of the coolant and dried to deposit the coolant in the filter pad. The effect is to give a pleasant cool sensation in the mouth when the cigarette is smoked. As little as 0.1 mg. of the coolant is effective.

Compositions of this invention are illustrated by the following Examples.

EXAMPLE I After Shave Lotion

An after shave lotion was prepared according to the following recipe by dissolution of the ingredients in the liquid and cooling and filtering:

    ______________________________________                                         Denatured Ethanol      75%                                                     Diethylphthalate       1.0%                                                    Propylene Glycol       1.0%                                                    Lactic Acid            1.0%                                                    Perfume                3.0%                                                    Water                  to 100%                                                 ______________________________________                                    

Into the base lotion was added 0.5% by weight based on the total composition of N,2,3-trimethyl-2-isopropylbutanamide. When the final lotion is applied to the face a clearly noticeable cooling effect becomes apparent after a short interval of time.

EXAMPLE II Eye Lotion

An eye lotion was prepared containing the following ingredients:

    ______________________________________                                         Witch Hazel           12.95%                                                   Boric Acid            2.00%                                                    Sodium Borate         0.50%                                                    Allantoin             0.05%                                                    Salicylic Acid        0.025%                                                   Chlorobutol           0.02%                                                    Zinc Sulphate         0.004%                                                   Water                 to 100%                                                  ______________________________________                                    

To the formulation was added 0.01%, based on the total composition of N-(2-isopropyl-2,3-dimethylbutanoyl)glycine ethyl ester. When used to bathe the eyes a cool fresh sensation is apparent on the eyeball and eyelids.

EXAMPLE III Toothpaste

The following ingredients were mixed in a blender:

    ______________________________________                                         Dicalcium phosphate    48.0%                                                   Sodium lauryl sulphate 2.5%                                                    Glycerol               24.8%                                                   Sodium carboxymethyl   2.0%                                                    cellulose                                                                      Citrus flavourant      1.0%                                                    Sodium saccharin       0.5%                                                    Water                  to 100%                                                 ______________________________________                                    

Shortly before completion of the blending operation 1.0% by weight N,N,2,3-tetramethyl-2-isopropylbutanamide was added to the blender. When applied as a toothpaste, a cooling effect is noticed in the mouth.

EXAMPLE IV Soft Sweet

Water was added to icing sugar at 40% to form a stiff paste. 0.5% of N-ethyl 2,2-diisopropylbutanamide was then stirred into the paste and the mixture allowed to set. A soft sweet mass resulted having the characteristic cooling effect in the mouth of peppermint but without the minty flavour or odour.

EXAMPLE V Cigarette Tobacco

A proprietary brand of cigarette tobacco was impregnated with an alcoholic solution of N-ethyl 2-isopropyl-2,3-dimethylbutanamide, dried and rolled into cigarettes each containing approximately 0.00025 gm. of active compound. Smoking the impregnated cigarettes produced a cool effect in the mouth characteristic of mentholated cigarettes.

A similar effect is noticed when smoking a proprietary brand of tipped cigarette, the coolant being used to impregnate the filter tip rather than the tabacco.

EXAMPLE VI Antiseptic Ointment

An ointment was prepared according to the following formulation:

    ______________________________________                                         Cetyltrimethyl ammonium 4.0%                                                   bromide                                                                        Cetyl Alcohol           6.0%                                                   Stearyl Alcohol         6.0%                                                   White Paraffin          14.0%                                                  Mineral Oil             21.0%                                                  Water                   to 100%                                                ______________________________________                                    

The ingredients were mixed, warmed to 40° C. and emulsified in a high speed blender. Added to the mixture during blending was 1.5% of N,N,2-trimethyl-2-isopropylhexanamide.

The final ointment when applied to the skin gave rise to a marked cooling effect.

EXAMPLE VII Aerosol Shaving Soap

An aerosol shaving soap composition was formulated according to the following recipe:

    ______________________________________                                          Stearic acid            6.3%                                                  Lauric acid              2.7%                                                  Triethanolamine          4.6%                                                  Sodium carboxymethyl cellulose                                                                          0.1%                                                  Sorbitol                 5.0%                                                  Perfume                  0.4%                                                  Water                    to 100%                                               ______________________________________                                    

The composition was prepared by fusing the acids in water, adding the triethanolamine, cooling and adding the other constituents. To the mixture was then added 0.5% based on the total composition of N,2,2-triethyl-3-methylbutanamide. The composition was then packaged in an aerosol dispenser under pressure of a butane propellent.

When used in shaving a fresh cool sensation was distinctly noticeable on the face.

EXAMPLE VIII Toilet Water

A toilet water was prepared according to the following recipe:

    ______________________________________                                         Denatured ethanol      75.0%                                                   Perfume                5.0%                                                    Water                  to 100%                                                 ______________________________________                                    

To the recipe was added 2.0%, based on the total composition, of N-ethyl 2-sec-butyl-2,3-dimethylpentanamide.

As with the after shave lotion, a cooling effect was clearly noticeable on the skin well after the termination of any cooling effect attributable to the evaporation of the alcoholic carrier.

EXAMPLE IX Deodorant Composition

A deodorant composition suitable for formulation and dispensing as an aerosol under pressure of a suitable propellent was formulated according to the following recipe:

    ______________________________________                                         Denatured ethanol      96.9%                                                   Hexachlorophene        2.0%                                                    Isopropyl myristate    1.0%                                                    Perfume                0.1%                                                    ______________________________________                                    

To the composition was added 2% by weight of N,N,2,2-tetraethyl-3-methylbutanamide. Application of the final composition gave rise to a definite cooling sensation on the skin.

EXAMPLE X Hair Shampoo

Sodium lauryl ether sulphate, 10 g., was dispersed in 90 g. water in a high speed mill. To the dispersion was added 2% by weight of N-(1,1-dimethyl-2-hydroxyethyl)-2-isopropyl-2,3-dimethylbutanamide. When the hair is washed using the shampoo a fresh, cool sensation is noticed on the scalp.

EXAMPLE XI Solid Cologne

A solid cologne was formulated according to the following recipe:

    ______________________________________                                         Denatured ethanol      74.5%                                                   Propylene glycol       3.0%                                                    Sodium stearate        5.0%                                                    Perfume                5.0%                                                    Water                  to 100%                                                 ______________________________________                                    

The sodium stearate was dissolved by stirring in a warm mixture of the ethanol, propylene glycol and water. To the solution was added the perfume and 2% of N,N,2-dimethyl-2-isopropylhexanamide and the mixture then allowed to solidify into a waxy cake.

When applied to the forehead a distinct cooling effect is noticeable.

EXAMPLE XII Mouthwash

A concentrated mouthwash composition was prepared according to the following recipe:

    ______________________________________                                         Ethanol                3.0%                                                    Borax                  2.0%                                                    Sodium bicarbonate     1.0%                                                    Glycerol               10.0%                                                   Flavourant             0.4%                                                    Thymol                 0.03%                                                   Water                  to 100%                                                 ______________________________________                                    

To the composition was added 0.1% of N-(1,1-dimethyl-2-hydroxyethyl)-2,2-diethylbutanamide.

When diluted with approximately 10 times its own volume of water and used to rinse the mouth a cooling effect is obtained in the mouth.

EXAMPLE XIII Toothpicks

The tip of a wooden toothpick was impregnated with an alcoholic solution containing N-ethyl 2,2-diisopropylbutanamide in sufficient amount to deposit on the toothpick 0.05 mg. of the compound. The impregnated toothpick was then dried. When placed on the tongue there is no detectable taste, however, a distinct cooling effect is noticeable after a short period of time.

EXAMPLE XIV Soft Drink

A soft drink concentrate was prepared from the following recipe:

    ______________________________________                                         Pure orange juice    60%                                                       Sucrose              10%                                                       Saccharin            0.2%                                                      Orange flavouring    0.1%                                                      Citric acid          0.2%                                                      Sulphur dioxide      trace amount                                              Water                to 100%                                                   ______________________________________                                    

To the concentrate was added 0.10% of N,2,3-trimethyl-2-isopropylbutanamide.

The concentrate was diluted with water and tested. An orange flavour having a pleasantly cool after-effect was obtained.

EXAMPLE XV Boiled Sweet

99.5% sucrose and 0.5% citric acid were carefully fused together in the presence of a trace of water. Just before casting the melt onto a chilled plate 0.5% of N-ethyl 2-methyl-2-isopropylhexanamide was rapidly stirred in.

The melt was then cast. A boiled sweet resulted having a marked cooling effect on the mouth.

EXAMPLE XVI Indigestion tablet

The following ingredients were ground together:

    ______________________________________                                         Magnesium carbonate     46.5%                                                  Sorbitol                49.4%                                                  Saccharin               0.1%                                                   Talc                    1.0%                                                   ______________________________________                                    

Added to the mixture during grinding was 0.10% of N-ethyl 2-isobutyl-2,4-dimethylpentanamide. After mixing the mixture was pressed into 0.5 g tablets.

Taken by mouth and swallowed the tablets produced after a short interval of time a noticeable cooling effect in the stomach.

EXAMPLE XVII Cleansing Tissue

A cleansing tissue was prepared having the formulation:

    ______________________________________                                         Triethanolamine Lauryl 1.0%                                                    sulphate                                                                       Glycerol               2.0%                                                    Perfume                .95%                                                    Water                  to 100%                                                 ______________________________________                                    

To this liquid was added 1.0% of N-ethyl 2-isopropyl-2,3-dimethylbutanamide. A paper tissue was then soaked in the liquid.

When the impregnated tissue was used to wipe the skin a fresh cool sensation developed on the skin after a short interval.

The above Examples illustrate the range of compounds and the range of compositions included within the present invention. However, they are not to be taken as limiting the scope of the invention in any way. Other compounds within the general formula will be equally suitable for use in the compositions of Examples I-XVII and the physiological cooling effect obtained with the compounds of the invention will recommend their use in a wide variety of other compositions where the cooling effect will be of value.

The following Examples illustrate the preparation of the novel compounds of this invention. All temperatures are in degrees Centigrade. The tertiary carboxylic acid starting materials were obtained by alkylation of nitriles by known techniques followed by hydrolysis.

EXAMPLE XVIII Preparation of N-methyl-2,3-Dimethyl-2-Isopropylbutanamide

2,3-Dimethyl-2-isopropylbutanoic acid (22 g) was heated under reflux with thionyl chloride (50 ml) for 60 minutes. The excess of thionyl chloride was removed under reduced pressure and the 2,3-dimethyl-2-isopropylbutanoyl chloride was distilled, bp. 73°-5°/15 mm.

A portion (2 g) of the acid chloride in ether (20 ml) was added dropwise to a stirred solution of ethylamine (5 ml of a 70% solution in water) in ether (100 ml.). The mixture was stirred for 1 hour. The ether layer was then washed with water, dilute hydrochloric acid and water. The dried (MgSO₄) ether solution was concentrated, and the residue distilled to give N-ethyl-2,3-dimethyl-2-isopropylbutanamide, bp. 93°-5°/1.5 mm, as a colourless liquid which rapidly solidified to a colourless solid mp. 38°-40°.

EXAMPLE XIX Preparation of N,2,3-Trimethyl-2-Isopropylbutanamide

The procedure of Example XVIII was repeated using methylamine in place of ethylamine. N,2,3-Trimethyl-2-isopropylbutanamide was obtained as a colourless solid, mp 58°-61°, bp. 83°-5°/0.35 mm.

EXAMPLE XX Preparation of N-(2,3-Dimethyl-2-Isopropylbutanoyl)-Glycine Ethyl Ester

Sodium bicarbonate (1.7 g, 0.02 mole) and glycine ethyl ester hydrochloride (1.4 g, 0.01 mole) were dissolved in water (10 ml) and a solution of 2,3-dimethyl-2-isopropylbutanoyl chloride (1.6 g, 0.009 mole) in ether (10 ml) was added. The mixture was stirred vigorously at room temperature for 2 hours. After 16 hours at room temperature the ether layer was separated and dried (MgSO₄). Removal of the solvent left a white solid which was recrystallised from ether/petroleum ether to give N-(2,3-dimethyl-2-isopropylbutanoyl)glycine ethyl ester, mp. 74.5°-75.5°.

Analysis: Found C: 64.0; H: 10.3; N: 5.9; Calculated C: 64.2; H: 10.3; N: 5.8%.

EXAMPLE XXI Preparation of N-(1,1-Dimethyl-2-Hydroxyethyl)-2,2-Diethylbutanamide

2,2-Diethylbutanoyl chloride was prepared from 2,2-diethylbutanoic acid and thionyl chloride in the usual way.

A solution of this acid chloride (1.2 g) in ether (30 ml) was added to a stirred solution of 2-amino-2-methylpropan-1-ol (4.0 g) in ether (90 ml). After 4 hours the ethereal solution was washed with dilute hydrochloric acid and water, dried (MgSO₄), and concentrated. The residue was distilled to give N-(1,1-dimethyl-2-hydroxyethyl)-2,2-diethylbutanamide, bp. 113°-5°/0.9 mm, mp. 57°-8°.

Analysis: Found C: 67.5; H: 12.0; N: 6.6; Calculated C: 67.0; H: 11.06; N: 6.5.

EXAMPLE XXII Preparation of N-Ethyl-2-Isobutyl-2,4-Dimethylpentanamide

2-isobutyl-2,4-dimethylpentanoyl chloride (bp. 97°-100°/16 mm) was prepared in the usual way from 2-isobutyl-2,4-dimethylpentanoic acid (prepared by the alkylation of ethyl cyanide with 2 equivalents of isobutyl bromide, followed by hydrolysis) and thionyl chloride. A solution of the acid chloride (1.5 g) in ether (20 ml) was added with stirring to a solution of ethylamine (5 ml of a 70% solution in water) in ether (100 ml). After stirring for 2 hours the ethereal layer was washed with dilute hydrochloric acid and water. The dried (MgSO₄) other solution was concentrated and the residue was recrystallised from petroleum ether (bp. 40°-60°) to give N-ethyl-2-isobutyl-2,4-dimethylpentanamide, mp. 71.5°-72.5°.

Analysis: Found C: 72.9; H: 12.3; N: 6.9; Calculated C: 73.3; H: 12.8; N: 6.6%.

EXAMPLE XXIII Preparation Of N-Isopropyl-2-Sec-Butyl-2,3-Dimethylpentanamide

2-sec-butyl-2,3-dimethylpentanoyl chloride (bp. 108°-110°/17 mm) was prepared in the usual way from 2-sec-butyl-2,3-dimethylpentanoic acid and thionyl chloride. A solution of this acid chloride (2.0 g) in ether (30 ml) was added with stirring to a solution of isopropylamine (2.0 g) in ether (100 ml). After 16 hours the external solution was washed with dilute hydrochloric acid and water, dried (MgSO₄), and concentrated to give a white solid. This solid was recrystallized from petroleum ether (bp. 40°-60°) to give N-isopropyl-2-sec-butyl-2,3-dimethylpentanamide, MP. 74°-6°.

Analysis: Found C: 74.3; H: 13.1; N: 6.2; Calculated C: 74.0; H: 12.8; N: 6.2%.

EXAMPLE XXIV Preparation of N-(2-Hydroxymethyl)-2-Sec-Butyl-2,3-Dimethylpentanamide

A solution of 2-sec-butyl-2,3-dimethylpentanoyl chloride (2.0 g) in benzene (10 ml) was added to a stirred solution of ethanolamine (2.0 g) in benzene (100 ml). After 16 hours the benzene solution was washed with dilute hydrochloric acid and water, dried (MgSO₄) and concentrated to give a pale yellow syrup. Distillation of this syrup gave N-(2-hydroxyethyl)-2-sec-butyl-2,3-dimethylpentanamide bp. 125°-130°/0.3 mm which slowly solidified on standing.

Analysis: Found C: 68.6; H: 11.6; N: 6.3; Calculated C: 68.2; H: 11.8; N: 6.1%.

EXAMPLE XXV After Shave Lotion

An after shave lotion was prepared according to the following recipe by dissolution of the ingredients in the liquid and cooling and filtering:

    ______________________________________                                         Denatured Ethanol      75%                                                     Diethylphthalate       1.0%                                                    Propylene Glycol       1.0%                                                    Lactic Acid            1.0%                                                    Perfume                3.0%                                                    Water                  to 100%                                                 ______________________________________                                    

Into the base lotion was added 0.5% by weight based on the total composition of N,2-di-sec.butyl-3-methylpentanamide. When the final lotion is applied to the face a clearly noticeable cooling effect becomes apparent from a short interval of time.

EXAMPLE XXVI Aerosol Shaving Soap

An aerosol shaving soap composition was formulated according to the following recipe:

    ______________________________________                                         Stearic acid             6.3%                                                  Lauric acid              2.7%                                                  Triethanolamine          4.6%                                                  Sodium carboxymethyl cellulose                                                                          0.1%                                                  Sorbitol                 5.0%                                                  Perfume                  0.4%                                                  Water                    to 100%                                               ______________________________________                                    

The composition was prepared by fusing the acids in water, adding the triethanolamine, cooling and adding the other constituents. To the mixture was then added 0.5% based on the total composition of N-ethyl-2-sec.butyl-4-methylpentanamide. the composition was then packaged in an aerosol dispenser under pressure of a butane propellant.

When used in shaving a fresh cool sensation was distinctly noticeable on the face.

The above Examples illustrate the range of compounds and the range of compositions included within the present invention. However, they are not to be taken as limiting the scope of the invention in any way.

Other compounds within the general formula will be equally suitable for use in the compositions of Examples I-XVII, XXV and XXVI and the physiological cooling effect obtained with the compounds of the invention will recommend their use in a wide variety of other compositions where the cooling effect will be of value. 

We claim:
 1. Monosubstituted aliphatic acyclic carboxamides of the formula ##STR5## where R₁, R₂ and R₃ are each C₁ -C₅ straight or branched chain alkyl and together provide a total of at least 5 carbon atoms; andR' is selected from C₁ -C₅ alkyl, C₁ -C₈ hydroxyalkyl and alkylcarboxyalkyl of up to 6 carbon atoms.
 2. Monosubstituted aliphatic acyclic carboxamides of the formula ##STR6## where R₁ is methyl, ethyl or n-propyl;R₂ is a C₃ -C₅ branched chain alkyl group having branching at the alpha- or beta-position; R₃ is a C₁ -C₅ straight or branched chain alkyl group; and R' is C₁ -C₅ alkyl.
 3. Monosubstituted aliphatic acyclic carboxamides of the formula ##STR7## where R₁ is methyl, ethyl or n-propyl;R₂ is a C₃ -C₅ branched chain alkyl group having branching at the alpha or beta position; R₃ is a C₃ -C₅ branched chain alkyl group having branching at the alpha or beta position; and R' is C₁ -C₅ alkyl.
 4. N-ethyl-2,3-dimethyl-2-isopropyl butanamide.
 5. N, 2,3-trimethyl-2-isopropyl butanamide. 